Three cone rock bit

Abstract

A three cone rock bit comprises legs and freely rotating cutters mounted on the same. The angle α between the projections of the rotational axes of two adjacent cutters on a plane perpendicular to the axis of the bit is more than 120° but less than 170°. A flow nipple to supply drilling fluid is provided in the bit, the outlet thereof being positioned between said two cutters.

What is claimed is: 
     
       1. An asymmetric three cone rock bit for drilling holes comprising: a bit head or body having an upwardly extending shank formed about a vertical axis or central axis of the bit body, and three horizontally spaced, downwardly projecting legs extending from said bit body; and generally conically shaped cutters of the same diametric size being journalled on each of said legs and extending downwardly and inwardly therefrom at the same cutter angle, each of said cutters being mounted on a leg for rotation about an axis projecting at an acute angle with respect to said vertical or central axis; said cutters and legs being asymmetrically positioned relative to each other wherein two of said cutters have rotational axes intersecting a plane extending normal to said vertical or central axis at two points spaced from each other by a greater distance than said points are each spaced from a third point of intersection with said plane of the rotational axis of the third cutter, and wherein said three points of intersection are used to define a circle in said plane; said two points of intersection are angularly spaced circumferentially from each other at an angle greater than 120° but less than 170°; and a single flow nipple or nozzle means for supplying of a flushing fluid extending downwardly between said two cutters to a position spaced close to the bottom of the drill hole, whereby the flushing action of fluid flow on the hole bottom is intensified and drilling performance is improved. 
     
     
       2. The asymmetrical three cone rock bit according to claim 1, wherein said angle equals about 144°. 
     
     
       3. An asymmetrical three cone rock bit according to claim 1, wherein said single flow nipple or nozzle means is adjustable so as to be fitted at an angle to the bottom of a drill hole.